Component feeding in automated assembly machines involves three aspects: (i) singulation, which is the separation of multiple components so they can be manipulated individually, (ii) orientation, which is the manipulation of components into a specific orientation required for the next processing step; and (iii) escapement, which is the controlled separation and transfer of components from the end of a line and insertion into a processing machine, e.g., an assembly machine at a specific spacing between components, as required by the processing machine. Escapement can also include additional aspects of singulation and orientation.
U.S. Pat. No. 3,601,041 describes an apparatus for feeding and orienting parts such as tablets or capsules. Capsules are carried by a hopper set over a rotating disc having slotted radial paths. As the capsules fall from the hopper onto the rotating disc, the are centrifugally thrown toward the outer periphery along the slotted paths and urged into the slots in an end-to-end aligned relation. The capsules are passed between printing members in their oriented position and then discharged into a hopper.
U.S. Pat. No. 3,471,000 describes a mechanism for orienting and feeding items such as fruit and produce to a location for packaging. A conveyor delivers the items to a rotating mechanism. The rotating mechanism includes a plurality of radial arms, which, at a certain point in a cycle of rotation, rise to place the item on a shelf that rotates simultaneously with the radial arms. When the shelf reaches a particular station, the item is urged into a chute or outlet. This cycle is continuous during rotary motion of the mechanism.
U.S. Pat. Nos. 3,912,120, 3,960,293, 4,821,920 and 5,740,899 also describe rotating mechanisms and apparatus for feeding, orienting, and/or separating articles.
As shown in FIG. 1, known escapement mechanisms involve an intermittent feeding, also known as “slice” feeding, of components into processing machines. That is, each component, or batch of components, is stopped or slowed to a momentary standstill so that they can be transferred and then inserted into the processing machine at a predetermined spacing between components. Thus, the time interval during which the components are stopped creates the required spacing.
In general, a transfer disk 20, with a number of component holders 22, rotates about an axis 24 in the direction of arrow 26. As each component holder 22 moves into contact with the end of a stream of components 28, the holder captures the component, and separates it from the stream. The remaining parts in the stream 28 advance rapidly to position or location 30 vacated by the one taken and wait for the next component holder 22 to advance to position 30. This time delay results from the predetermined spacing 32 between the component holders 22 and thus between the components 28 as they exit the transfer disk 20 at location 34. As seen in FIG. 1, the distance along the curve between component holders 22 on disk 20 is essentially the same as the distance between the components after they exit the disk at position or location 34.
This slice feeding mechanism provides the required spacing between components, but requires that all components stop, one after the other. This process is thus wasteful in terms of energy and time, and significantly limits the overall processing speed. In addition, the jarring of components when they stop can lead to damage of the components and can impair their orientation, which is particularly important when working with asymmetrical and aspherical components that are processed at high speeds.